CAIRO (AP) -- Egypt's embattled president on Friday dismissed calls for early presidential elections as clashes erupted in a northern Egyptian city and unidentified assailants torched a Cairo campaign headquarters of a youth group petitioning for Mohammed Morsi's removal from office.
The developments come as tensions rise ahead of June 30, when Morsi marks one year in power as Egypt's first freely elected president following the 2011 uprising that toppled autocrat Hosni Mubarak.
Clashes erupted Friday evening in downtown Cairo between security forces and members of the Black Block, a group of young masked men opposed to president Morsi's rule. Protesters hurled stones at the Central Security forces who fired back tear gas, according to the MENA State news agency.
Violence has become a common feature of politics in Egypt. Over the last two years, several marches and rallies by the country's various camps have deteriorated into street battles.
In a four-page interview with the state-run Al-Ahram daily ahead of the anniversary, Morsi said demands for an early presidential vote are both "absurd and illegal." He also warned against violence during upcoming demonstrations, which the opposition plans for the anniversary to demand his ouster.
"Violating the law, the use of violence or inciting for it are unacceptable and will not be permitted," Morsi told the paper on Friday. "We are in a country with a constitution and law. We had free and fair elections and the talk about early presidential elections is absurd and illegal."
The lengthy interview was a throwback to Mubarak's era when the paper served as a government mouthpiece, glorifying the regime's perceived successes and never challenging authorities.
Before dawn Friday, attackers stormed and partially torched the downtown Cairo headquarters of a volunteer youth group running a petition calling for Morsi's removal from power.
The drive, known as "Tamarod" or "Rebel" in Arabic, is helping galvanize an opposition that has long been in disarray and demoralized. So far, the volunteers say they have collected about 7 million signatures.
They hope to collect 15 million signatures and believe that such a large number would force Morsi out of office by June 30. The figure would be 2 million more than the number of votes Morsi garnered in last year's presidential election, which he won with 52 percent of the votes. Egypt's population is around 90 million.
The volunteer group said it had received threats prior to the 3:30 a.m. attack, alerting some activists to stay overnight at the office.
"We were awakened by someone trying to break the door and the glass and then we saw fire under the door, coming at us," said Hassan Shahine, one of the campaign founders.
Shahine, who suffered light burns trying to extinguish the fire, blamed Morsi's Muslim Brotherhood for the attack, saying the president's party is "the only one who would think of doing this." The volunteers filed a police complaint against Brotherhood leaders after the attack, he added.
A Brotherhood spokesman, Mourad Aly, dismissed the accusations, saying the group has no reason to "burn the office of a group (of activists) as weak as this."
In a separate incident, women activists accused the Brotherhood of attacking them while attending a conference organized by the group in the Nile Delta city of Damanhur, 85 miles north of Cairo on Thursday night.
Video clips circulating on social networking sites showed bearded men wearing helmets at the site shouting "Allah Akbar," or God is Great, while carrying sticks and hurling rocks. The identity of the men is not clear. The website of the Brotherhood's political party said anti-Morsi activists were the ones who assaulted conference attendees.
Activist Hadir el-Sharkawi said Brotherhood members "beat us up and sexually harassed women including one who was stripped of her trousers." She said security personal were present but did not intervene.
The Brotherhood's Aly denied the allegations, saying "we are not going to delve into every single accusation."
During Morsi's tumultuous year in power, Egypt has witnessed deadly bouts of violence and mass street protests while the country's economy plummets and security woes worsen.
Egypt's liberal and secular-minded opposition accuses Morsi and the Brotherhood of causing deep polarization among Egyptians. It says the president has not fulfilled his promises of creating an inclusive political process and instead has been enabling his Brotherhood to monopolize power.
For their part, Morsi and the Brotherhood say the opposition has no grass-roots support and seeks to unseat the president through street protests and violence after failing at the ballot box.